Modern pickup trucks have extended cabs capable of sitting five passengers comfortably. The boxes of these modern pickup trucks have a length of 6 ft.-6 in., basically. These short boxes cannot transport trail-type or mountain-type snowmobiles with lengths of 11 and 13 feet respectively, even with the tailgate in the open position. Similarly, lumber and other residential construction materials are sold in 8, 10 and 12 foot lengths. Transporting these materials in a short-box pickup truck can sometimes be a challenge. For these reasons, it is believed that modern short-box pickup trucks have created a market need for truck bed extension decks that can be used to transport material and equipment that is best transported in a conventional 8-foot truck box.
Conventional ramps for use with pickup trucks have a length of 8 feet. It is generally accepted that an 8-foot ramp provides an easy slope for loading a vehicle in the truck box. Short truck boxes are inherently associated with shorter ramps and a steeper climbing angle for loading sport or gardening equipment in the truck box. This inconvenience also points to a market need for truck bed extension decks that can be used to transport material and equipment that is best transported in a conventional 8-foot truck box.
In another aspect of truck bed liners, the most important factor in the design of a truck ramp and truck-bed liner or extension deck, is a weight-to-strength ratio of the deck itself. A truck owner does not want to carry extra weight in his truck and to spend unnecessary fuel. On the other hand, the buyer of a truck bed liner and ramp assembly wants this equipment to be strong, durable, usable and safe. In that point of view, a frame that is made of flat bars mounted on their edges offers the best weight-to-strength ratio, when compared to hollow structural tubing or structural angles of a same weight per foot for example. Despite this advantage, it is believed that a framing system made of flat bars in a truck bed liner has not been used in the past.
A number of truck-bed liners with and without ramps have been found in the prior art. It is believed that the following documents provide a good inventory of these previous inventions:    U.S. Pat. No. 4,573,731 issued to H. L. Knaack et al., on Mar. 4, 1986;    U.S. Pat. No. 4,601,632 issued to J. H. Agee on Jul. 22, 1986;    U.S. Pat. No. 4,624,619 issued to M. L. Uher on Nov. 25, 1986;    U.S. Pat. No. 4,685,857 issued to M. N. Goeser et al., on Aug. 11, 1987;    U.S. Pat. No. 4,722,109 issued to E. E. Mountz on Feb. 2, 1988;    U.S. Pat. No. 4,733,898 issued to S. D. Williams on Mar. 29, 1988;    U.S. Pat. No. 4,900,217 issued to J. N. Nelson on Feb. 13, 1990;    U.S. Pat. No. 4,990,049 issued to J. F. Hargrove on Feb. 5, 1991;    U.S. Pat. No. 5,257,894 issued to H. K. Grant on Nov. 2, 1993;    U.S. Pat. No. 5,393,192 issued to J. C. Hall et al., on Feb. 28, 1995;    U.S. Pat. No. 5,468,114 issued to S. J. Hickerson on Nov. 21, 1995;    U.S. Pat. No. 5,533,771 issued to S. Taylor et al., on Jul. 9, 1996;    U.S. Pat. No. 5,570,989 issued to M. Belanger on Nov. 5, 1996;    U.S. Pat. No. 5,795,125 issued to C. D. Walkden on Aug. 18, 1998;    U.S. Pat. No. 5,863,173 issued to R. A. Bremner on Jan. 26, 1999;    U.S. Pat. No. 6,464,274 issued to F. L. Mink et al., on Oct. 15, 2002;    U.S. Pat. No. 6,484,344 issued to S. M. Cooper on Nov. 26, 2002;    U.S. Pat. No. 7,128,357 issued to N. C. Carroll on Oct. 31, 2006;    CA Patent 1,033,313 issued to J. L. Glassmeyer on Jun. 20, 1978;    CA Patent 1,284,564 issued to D. Manning et al., on Jun. 4, 1991;    CA Patent Appl. 2,076,255 published by G. O. Alexander on Feb. 18, 1994;
It is believed that a market need exists in the field of truck accessories for a foldable bed extension deck and ramp assembly having a good weight-to-strength ratio, and that can be mounted in a short-box pickup truck to provide the same advantages as those of a full size truck box, while preserving the integrity of the tailgate of the pickup truck.